<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>vue</title>
    <script type="text/javascript" src="../../js/vue.js"></script>

</head>
<body>
    <div id="root">
        姓：<input type="text" v-model="firstName"> </br>
        名：<input type="text" v-model="lastName"> </br>
        全名：<span>{{firstName.slice(0,3)}}-{{lastName.slice(0,3)}}</span>
    </div>

    <script type="text/javascript">
        Vue.config.performance = false;
        const vm = new Vue({
            el:'#root',
            data() {
                return {
                  firstName:'张',
                  lastName:'三'
                };
            },
        })

    </script>

</body>
</html>